This invention relates to a method for forming, in a cigarette packeting machine, incomplete groups of cigarettes which constitue the contents of respective packets.
The packets produced by packeting machines normally comprise twenty cigarettes distributed in three adjacent, superposed layers. However, said packeting machines are normally adjustable in order to produce packets of different formats containing a number of cigarettes which normally varies between ten and twentyfive, and distributed in at least two superposed layers.
The continual variation in the selling price of cigarettes and the increasingly extensive use of automatic cigarette vending machines have made it increasingly more necessary to produce packets of cigarettes which, although having the same format and thus using the same wrapping material and the same types of vending machines, can contain a variable number of cigarettes so as to keep their selling price substantially unchanged over a relatively long period of time and/or to adjust the said price to a determined size of currency note so as to avoid the automatic dispensing of change.
Hereinafter, the term "incomplete" is used to indicate a packet of cigarettes, a group of cigarettes constituting the contents of a packet, or a layer of cigarettes of said group, in which at least one of the cigarettes is missing.
With reference to the aforesaid problem, the term "incomplete" will therefore be used to define those packets, groups and/or layers of cigarettes which are obtained by eliminating at least one cigarette at the formation stage in such a manner that the resultant incomplete packet retains the overall dimensions and thus the wrapping of the corresponding complete packet, but contains one or more cigarettes fewer.
In known packeting machines, the formation of incomplete packets of cigarettes normally involves certain difficulties for the obvious reason that such machines are designed for forming complete packets, and all their mechanical and safety characteristics are conceived for this purpose.
The aforesaid applies particularly to that part of the said known packeting machines used for forming the groups of cigarettes which are then wrapped in order to form the packets. In this respect, the said groups are generally formed starting from a plurality of side-by-side hoppers, the number of which is equal to the number of superposed layers of cigarettes contained in each group.
Each of the said layers is formed on the base of the respective hopper and is fed into a group formation and conveying pocket, which is mobile with stepwise movement in such a manner that it halts in succession in a position facing each of said hoppers. The base surfaces of these latter are disposed at gradually increasing levels to enable the cigarettes withdrawn from one hopper to lie on the cigarettes withdrawn from the preceding hopper.
During their withdrawal from the respective hopper, the cigarettes are thrust axially by a pusher out of said hopper and into the relative pocket, the advancement movement of which takes place in a direction transverse to the cigarette axis. The insertion of the cigarettes into the relative pocket and their sliding over the immediately lower layer already disposed inside the pocket are favoured by the presence of a guide plate which extends above said lower layer to cover an initial portion of the cigarettes thereof and to prevent any interference.
Once inserted, the cigarettes of one layer stop against a stop wall so as to lie exactly over the cigarettes of the lower layer, and are halted against these latter by a lateral stop element which is lowered on to the cigarettes so as to keep them in position against the cigarettes of the lower layer and within the relative pocket when this latter undergoes a further forward step.
Because the said guide plate, which is mounted in a fixed position below the respective hopper, remains between the layer which has just been fed and the immediately lower layer, the terminal parts of the cigarettes of the said two layers in contact with said plate undergo sliding when said pocket advances through one step.
This fact does not constitute a drawback when complete layers are formed, but is absolutely damaging when incomplete layers are formed because the friction against said plate, although of negligible value, is sufficient to transversely displace the cigarettes of a layer when this latter comprises voids.